. Form the pair of linear equations in the following problems, and find their solutions graphically


(i) 10 students of Class X took part in a Mathematics quiz. If the number of girls is 4 more than the number of boys, find the number of boys and girls who took part in the quiz.

(ii) 5 pencils and 7 pens together cost Rs 50, whereas 7 pencils and 5 pens togethercost Rs 46. Find the cost of one pencil and that of one pen.

 

 


 

 

Best Answer

Solutions :

i. Let number of boys = x

Let number of girls = y

According to the question,

= x+y = 10

= x = 10-y

Putting y = 0 , 5, 10 . we get,

X = 10 – 0 = 10

X = 10 – 5 = 5

X = 10 – 10 = 0

pair of linear equation

ii. Let cost of one pencil = Rs. X

Let cost of one pen = Rs. Y

According to the question,

= 5x+7y = 50

= 5x = 50-7y

= x = 10-7/5

Putting value of y = 5 , 10 , 15 we get,

pair of linear equation

 


 

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